The Big Think

July 9, 2016

The R2 Project: My Feet Are Killing Me

Filed under: The R2 Project — jasony @ 9:57 pm

Not my feet, actually. R2’s feet. When I look back on the 5ish years that I’ll spend doing this crazy project I believe that “Tig Welding the Feet” will probably be one of the hardest parts. I have spent 77 hours practicing TIG and used almost 500 feet of welding rod. Not sure what that translates to in actual weld length since there’s not a 1:1 relationship between rods and weld beads laid down, but it has got to be close to 1000 feet. In the last week I’ve spent nearly 15 hours under the hood welding parts. And, oh, what parts.

I’m currently working on the foot shell assemblies. These:

R2d2 feet

R2d2 third foot

There are two outer feet (the top picture) and one center foot (bottom pic). All aluminum. The side details are applied later, as are the vertical strips on the ends, but the rows of rectangles around the bottom skirt are part of the assembly.

So far it has taken 13 hours to weld up the center foot and it looks great. I ground it down (2 hours) and noticed that some of my welds hadn’t penetrated enough, so I had to go back and re-weld everything. I really hope that I did it right. Grinding isn’t fun.

The side feet (the top pic above) has been a real bear. Everything wants to warp and crack and the shape is just a crazy one to start with with a 3″ diameter curve and a delicate little edge on the backside (of this pic). Several times I found myself wanting to slap whoever designed this part. The curved edge in particular has been it’s own special joy. I tried to bend the part using a hydraulic press but just couldn’t get it to fit correctly, which meant that I had to toss the part and start over. This time I spent 13 hours milling the curve on the manual mill, as well as the bottom corner piece. Then when I welded it all up the pieces warped so badly that I had an air gap, so I had to grind most of the corner bit (which I had gotten accurate to .004″) so that I could weld in a patch.

This frustrating part has been bedeviling me for several weeks now, but I think I see a light at the end of the tunnel. I spent 11 hours at TechShop today (I had a 4 hour water jet class in the middle) doing nothing but welding. I still have to grind, but here’s what I did:

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It’s upside-down in this picture since I weld better right-to-left and that top weld was the last one I did. There was a point tonight around hour 5 where I felt like I clicked up to the next level. My coordination with the pedal, rod, and torch was much better, I was able to direct heat into tiny little areas without melting nearby edges or corners, and, most importantly, I even bridged a 1/4″ gap and created new metal to do it. That’s pretty advanced. Basically, even with my patch I still had a couple of spots that gapped. I had resigned myself to using lab metal to fill them in. However, I was welding so well that when I got to that spot I just said screw it and dove right in. In hindsight I could have really messed things up but I guess I was feeling confident. Well, I absolutely nailed it, adding in several cubic centimeters of new metal by pushing the rod into the puddle before it had a chance to drip or ooze away. I nearly whooped for joy! You can see the spot where I did that in the above pic. It’s the upside down corner nearest the camera where the curve meets the edge. I did a similar spot on the back side and got that as well. BOOM!

Once this piece is ground down (a long and messy job) I’m sure there will be a few spots that I’ll have to go back and patch up. Then I’ll have to grind it down again to finish the part. These feet have been a struggle at every point and I consider it one of the hardest and most satisfying things I’ve ever done from a maker/builder standpoint. I still have one more foot to go (ugh!) and it’ll be a month or two before they’re all ground down, rewelded, and reground. I’ll post pics then.

In the meantime, here’s a picture of the whole leg stack coming together. I ground the welds on the main leg box and it looks like one solid piece! That’s what the rest of them will look like once I’m done. This pic has the leg assembly, horseshoe, ankle, battery box, and foot shell. I stacked this together tonight and nearly cried. 🙂

TIG welding aluminum! Can’t believe it.

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June 18, 2016

R2 Battery Box #2

Filed under: The R2 Project — jasony @ 6:53 pm

Tig welded up battery box #2 today. Complete success! I did some quick and dirty JB weld spots to hold the loose pieces together while I did the tack welds. Unfortunately, the JB melted in spectacular fiery fashion (complete with noxious fumes). Good thing we have vent hoods. Ick. 

I did some fast reclamping and got the tack welds in. From that stressful step on, though, it was smooth sailing. Kind of contemplative and relatively easy. I also laid one bead down that looks as good as anything I’ve seen on the pro welding sites. For that 6″ I was a Weld Master. The rest of it wasn’t as pretty but will still do the job.

Also, I managed to get the hang of vertical welds! That’s huge as up to now I’ve had to figure out a way to position everything horizontally. Still not good at them but they’re not catastrophic fails.

So that makes all three ankles, both shoulder horseshoes, both legs, and both battery boxes welded up! Now I have to do the three feet over the next week or so. After that will come the grinding. Oh… the grinding. I’ll be at that for a long time. After the grinding I’ll have to go touch up some welds, but all the parts should look seamless.

Really pleased with my progress.



June 10, 2016

Leg Welding, Burned Boots, and R2 Takes His Pound of Flesh

Filed under: The R2 Project — jasony @ 10:40 pm

Major progress the last few days and I even got a decent little injury to show for it (more on that later).

I’ve been practicing my TIG welding for around 40 hours and decided to just go ahead and give the leg welding a try. Before I did that, though, I had to strip the old anodizing from the parts. I’d gotten the 1/4″ metal for free when I had the frame anodized black. The only downside was that the two sheets of free metal were clear anodized, and since you can’t weld anodized metal I had to strip the parts in a concentrated lye bath.

First a 10 minute dip in the hot lye solution, constantly agitating each part while the anodizing was dissolved (but not too long or the aluminum will be eaten away!), followed by a neutralizing bath in vinegar, then a water rinse/soak, then pressure washing each part to remove residue. At the end of this 4 hour process all the clear anodizing was gone.

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I doubled up on protective gear. Lye is nasty stuff.

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Then into the welding bay! It took me 5 hours to set up and tack all of the parts in the first leg just on one side of the leg. A tack weld is when you just do a quick spot weld in a few places to hold the parts together firmly– once they’re tacked you then go back over and run beads that hold everything together. Tack welds are a pain because everything wants to shift and slide around and it’s hard getting all of the loose parts to behave until they’re secured. And at the tolerances I’m dealing with I have to get them all positioned as close to perfect as I can.

This took me five hours to tack weld just one side. I was holding the torch sideways (a hard angle), I kept dipping my tungsten rod in the molten aluminum (necessitating regrinding of the tungsten), and just generally going glacially slow. It sucked. It was very frustrating. I felt like I’d forgotten everything I’ve learned about welding. It was a frustrating session.

But then yesterday I went back in and tacked the other side of the leg on and then ran beads. They weren’t the prettiest welds I’ve ever done, but once I got the aluminum hot it welded pretty well. Success! Felt great. No, it felt fantastic. Erin brought home some ice cream in celebration. Yum.

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Seven and a half hours…. for one leg!

Tonight I went back in to Techshop and set everything back up again. It generally takes me an hour to get the TIG bay ready to rock. I had to grind the edges of the 2nd leg parts, clean them with Alumiprep 33, rinse with water, scrub with a stainless brush to remove the remaining oxides, and then clean with acetone a final time.


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You have to have aluminum as surgically clean as possible, with zero oxidation, before it’ll weld correctly. Any contamination and things go south very fast. I decided to clamp everything together tonight before I tack welded and it went much faster. I was able to tack weld around the perimeter of the whole piece in about an hour and a half, then remove the clamps and run beads in a couple of hours. All told, I finished the second leg in just about 5 hours. Much faster

And something funny happened a few hours into welding. Suddenly all of this practice I’ve been doing the last few weeks just…. clicked. When TIG welding, you have to control the torch angle and speed with your right hand, the distance of the tungsten rod to the surface (around 1/16th inch separation is really hard to hold), the angle and speed of the aluminum rod you’re dipping into the molten pool with your left hand, and the torch power with your foot. It’s a lot to keep track of and if you change one of the factors then the equation alters and the weld pool does weird things. Tonight I was like Daniel-san after waxing on/off Mr. Miagi’s car for hours. Suddenly it just got a lot easier and I was like Neo in the Matrix watching the bullets come down the hallway. It was weird and fun and exciting. As a result I put down some of my best weld beads I’ve ever done. I could watch the puddle form and actually control where it was going. Things were predictable and I had a more subconscious sense of what to do when things went a little wrong. It was like that feeling when, after months on training wheels, you take them off and your body just “knows” how to balance on a bike. I’m sure I got great weld penetration down into the metal and everything cooperated. I got it, and it was a blast.

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One funny thing happened, though, when a glob of molten aluminum dropped free from the leg and disappeared between the slats of the table down toward the floor. Hmm… hope that doesn’t hit anything important. I then smelled burning fabric for a few seconds, then nothing. So I kept on welding. Later I noticed a 3/4″ long scar right in the top of my new Zamberlain leather hiking boot! So my right boot toe has a brand from R2. It’s not very noticeable and didn’t do any structural damage and kinda makes me smile when I look at it. That mark has a story. Kind of like the scars you get on an adventure: some you love for the stories they tell. No biggie.

The worse one today was when I was finishing up a weld and used my left hand (the one holding the super hot aluminum dipping rod) to raise my welding hood. Unfortunately, the rod got caught on the mask, popped up under my hood, and smacked me right in the upper lip.

While semi-molten.

So now my upper lip has a nice little burn mark and blister right smack dab in the middle at the very top. The lower lip got hit as well but didn’t get burned as badly. I hollered and hopped around for a minute, ran some cold water on it, and then hit it with some burn cream with 2% lidocaine. It’s numb right now and will take several days to heal and probably won’t scar. The joke around the R2 builder’s board online is that R2 requires a blood sacrifice every so often. Guess it was time. Working with 160 amps and 12,000 degree plasma, though…. it could have been much worse.

So anyway, the leg welds are done! I’ll need to spend a day or two grinding them down, but this is a huge step that I’ve been stressing about for over a year. I never thought I’d be able to learn TIG welding and seriously considered jobbing it out. I’m really glad I stuck it out and did it myself. So satisfying.

Next step is the foot assemblies and then the battery boxes. There’s still a lot of welding in my future. Once all that is done I’ll grind everything down (I am not looking forward to that day…those days) and then back fill any minor holes with Lab Metal, then sand it to a decent finish. I’ll still be throwing the legs on the mill for various operations (tapping, some more drilling, etc), so I won’t go crazy on the finish work until they’re all done.

Still, a really good week, in spite of the sartorial and facial scars. I’m really proud of what I’ve done.


June 1, 2016

Outer Ankle Solo Welding

Filed under: The R2 Project — jasony @ 7:37 pm

I spent another 4 hours at the TIG welder today (for a total of 34 hours) and did my first solo TIG part! I did one of the outer ankles and it took me the whole time.

Once I got all set up and ready I took the ankle layers into the machine shop and used the 90 degree jig and a flat plate to stack the parts so that they lined up exactly. One of the issues I discovered on the center ankle that I did with Keith last week was that I rushed the setup and the ankle is now just barely skewed. It’ll still fit its mounting bracket but I have to persuade it slightly. No big deal since the part that’s off is up inside next to the frame where you can’t see it. The outer ankles are much more visible so it was more important that I get those just right.

Once the layers were aligned and clamped tightly I brushed them with the stainless wire brush and then some acetone to get them perfectly clean, then I hit them with 150 amps of TIG POWER! Since the parts were room temperature, and since aluminum is such an incredible heat sink (ever wonder why your pans are aluminum?), I had to concentrate all of that power into a few spots for almost four minutes before the part heated up enough to start puddling. That part got hot. Unfortunately, the Lincoln 225 TIG machine I’m using is rated at a 40% duty cycle, and after about six minutes it went into overheat shutdown mode.


So I had to wait almost 10 minutes for the machine to cool down before I could continue welding. Fortunately, the ankle part is so dense that it lost heat slower than the welder cooled down. Otherwise it would have been a losing race. Still, I managed to overheat the machine two more times before I finally got into the groove. I’d weld a few lines (about 3″ per line), then put the torch down to let it cool a bit and inspect my work. Eventually I got the timing right and didn’t have any problems after that.

The end result is that I welded up the ankle to a good degree. There are still some holes but instead of torturing the part with super high heat for another hour or two (which can weaken aluminum), I’ll eventually fill the remaining v-grooves with Lab Metal and then Rage Pro body filler (high end Bondo).

I’m going to grind down the welds and inspect them to make sure that I got good penetration into the v-grooves. I was using 3/32″ 4043 filler rod but suspect that many of my welds are just on the surface. If, after welding, this turns out to be the case then I’ll have to go back in and re-weld so that the part is strong enough and I don’t get stress cracks once it’s painted.

For the other ankle I’m going to preheat the part in the powder coating oven until it hits a 200 degree surface temp, then move it to the welding bay and start TIGging it immediately. Hopefully then the welder won’t shut down and I can get the welds done sooner and not torture the poor part.

I won’t grind the welds down until I get my super breathing mask in from Amazon. I figured $24 was a small price to pay for not inhaling aluminum dust.

After the ankles are done I’ll move on to the leg boxes, which look to be slightly easier (less heat-sink-ey since there’s less metal) as well as more harrowing since I haven’t been walked through the part by Keith. But I’m slowly gaining confidence and know what to look for. I might practice on some 1/4″ first, though, to see how it behaves. I’ll be right next to the edge the whole time and don’t want to blow an edge out. Oy.

I can say that the last 30+ hours has been tremendously educational, and Keith’s help was very, very appreciated. He wouldn’t take any money for helping me after I told him that I’d like to take R2 to a Children’s hospital. He just flat refused (he’s a softy). So I’m donating $50 in his name to the St. Jude’s Cancer Center via Baylor Tri Delta (that’s their sorority charity). I’m sure Keith will cry when I give him the card. 🙂

In the meantime, here are some pics from my work today. Pretty happy with progress, though it remains to be seen if those welds are deep enough.

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Ankle attached to leg box! Box still has to be welded up.
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May 23, 2016

R2 Aluminum Pile

Filed under: The R2 Project — jasony @ 9:29 am

That’s a great big old pile of aluminum:

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What you’re seeing here are all the aluminum parts I’ve milled, water jetted, lathed, and otherwise mashed up since last September (really since about February). 

Starting from the left are the leg boxes, horseshoes, ankles (bottom left), battery boxes, and ankle bracelets. Then on the right hand side are the feet (all spread out on the table).

I opted to let Big Blue Saw cut the water jet files for the feet since it wasn’t that much of a premium and since they would replace any pieces that were messed up. Overall I think this was the wiser course even if it wasn’t immediately cheaper. It was cheaper in the case of the water jet making a mistake (something that happens about 10% of the time at TechShop). Even so, there are 90+ pieces of the feet (center foot and two outer feet) that have to be welded.

And oh, the welding. Most of the above pieces except for the horseshoe at the upper left still need to be TIG welded. There are 174 remaining pieces that will need to be cleaned, aligned, clamped, and TIG welded. I’m not sure of the total length of welds but it’s a lot and I’m sure I’ll be at it for months. Fortunately, except for two pieces, all of the machining and cutting is pretty much done for this year. Once the feet are welded I have to cut some pipe to size and then lathe, cut, and mill out a weird piece. Then once all of what you see here is done I’ll begin designing and cutting/welding the foot motor mounts. I think I’m going to do those custom but I’m still thinking about it. That’s for later.

My goal is to finish all of this by September but I still don’t have a good handle on how long the welding will take. I’m going to put in a few more 4 hour sessions practicing before I try and tackle an expensive-to-replace part. I’m going to hopefully get a one-on-one lesson with Keith at TechShop this weekend. He’s the good welder from my previous posts (one of the best in Austin). Then I’ll go through the pile of parts and start welding up assemblies from easiest to hardest, thereby gaining experience as I go. I suspect the battery boxes are going to be the hardest so they’ll be last.

I’m thinking that I’ll end up missing my September deadline as things progress since I haven’t even included time to correct the leg boxes on the mill (long story for a future post), drill and tap holes for mounting the horseshoes, drill out the ankles and install bushings (no idea how to do that), and probably spend two or three long sessions making the funky curved parts for the outer feet. Oh, and I also need to research how to remove anodization with a lye bath. Got some industrial strength lye (and a pile ‘o protective gear) to remove that but I’ll need to do a practice session on some scrap to make sure I have the procedure down correctly. 

Then it’s on to the foot motor assemblies, which I’m kind of looking forward to. I’ll need to commit to the motors (I’m thinking a pair of NPC2112 motors — they’re pricey but they represent “real” robotics motors instead of hacked up scooter motors). I’ll get those soon and then start designing the motor mounts. The feet need to be welded up first, though, so that I can make sure that I have enough clearance inside the shells.

Going to TechShop this morning for a 4 hour TIG practice session. I’m running out of scrap and will probably drop by Metals4U and get some .125” pieces (hopefully from their scrap pile) to continue practicing.

May 11, 2016

TIG Success!

Filed under: The R2 Project — jasony @ 7:06 pm
Best day TIG welding so far. I went through five filler rods (about 30′ of material) and didn’t mess up my tungsten once. Got some really nice welds laid and also ground them down flush so they look nice and pretty.

I did a drop test on the dummy part and determined that I need to grind the channels between the layers a little deeper to get better holding between the layers. But otherwise I’m actually ahead of where I thought I’d be after only 12 hours of practice! Very encouraged.

TIG Welding

I spent 10 hours at TechShop today. 4 doing welding practice and the rest grinding and prepping the parts for welding. Really successful day.

May 10, 2016

R2 Outer Ankles

Filed under: The R2 Project — jasony @ 9:19 pm

I’ve spent the last few days (post concussion) designing and tweaking the design for Artoo’s Outer Ankles. The water jetted layered .25″ aluminum trick is working nicely. I still have to TIG weld everything but Keith was able to TIG the .125″ horse shoes a few weeks ago and it worked well.

Today I checked out the water jet and spent four hours cutting 21 parts for the outer ankles. I had to remake one part since I didn’t clamp down the metal well enough and the edges were really jagged and messed up. I could have maybe dealt with it while welding but I decided to spend the extra three bucks and just cut another one. Total price for the outer ankles was just over $50 for the water jet time. The reason it took so long (4 hours!) was because I cobbled together a bunch of scrap aluminum that I’d used on other parts. I got all the parts in on scrap! This saved me probably $50 extra dollars in aluminum and let me clear some cruft out of my locker. Keep in mind that I’ve now done all three ankles (one center and two outer) for about $120. If I bought these over the internet from one of the suppliers they’d have cost me over $900!

In fact, I just looked at my master budget sheet and if I just look at Year 2: Legs I can get a sense of just how much I’m saving making the parts myself. Here’s the going price on the internet if I just bought the aluminum leg parts that I’ve made so far:

Leg boxes: $900
Horseshoes: $450
Ankles: $900
Ankle Bracelets: $30

So if I’d have just laid down the dough I’d be looking at almost $2500. I’ve spent less than a fifth on the legs. From here I still have to do the feet and the drive mechanisms, which would add another $1800 if I bought them…. and which I’ll get for an even better fraction.

So yeah… building it yourself is definitely the way to go, and the skills you pick up can’t be beat.

Speaking of which, I’m into my TIG welding practice. I’ve spent 8 hours at the TIG and can just now barely succeed (sometimes) at not embarrassing myself. But if I can just break through to reliably making two or three inches of halfway decent welds then I’m home free. I’m saving a bunch of offcuts and scraps of aluminum in various thicknesses to practice on. My plan is to make all the parts for the legs– horseshoes, ankles, leg boxes, feet, etc– but not weld any of them. Once the parts are made I’ll then dig in for several weeks of slow and methodical welding on each part. All I have to do is one or two inches at a time, let things cool, then repeat. I figure I probably have 200 feet of welds to do. It’s gonna take a while.

But slow and steady wins this race.

I may not be the most talented guy at any particular thing, but what I lack in ability I make up for in sheer stamina. I figure if I can stay with this R2 build for a half decade then really nothing is outside of my grasp.


April 25, 2016

R2 Ankle Breakthrough!

Filed under: The R2 Project — jasony @ 8:57 pm

After sitting and pondering and sitting and thinking and sitting and staring off into the distance for far too long I think I have finally cracked the center ankle problem. This whole time I’ve been trying to figure out how to make this shape:


from either a solid billet of aluminum (expensive and hard with many chances to break bits), or by forming/welding a rectangular bit of channel and then welding onto a solid hunk of aluminum for the curvy bits. The problem with the second approach is that aluminum is such a good conductor of heat that the thin walled channel will overheat and melt before the solid hunk even gets up to melting temp. A true welding pro can do it, but me? Not even close.

So what to do, what to do? More sitting and staring off into the distance, and then a long, slow walk around Techshop. I do my best 3D thinking while moving.

Then I looked at the layered horseshoe assembly I’ve been working on and thought OF COURSE! Could I adapt that idea to the center ankle?

So I used Fusion 360 to design the two different layer shapes, exported them as .dxf files into Illustrator, checked the geometries, did a little bit of redesign on the interior of the foot, and then dropped them onto the laser cutter with some 1/4″ plywood for a proof of concept. The plywood was being stubborn and didn’t cut too well (and there was a guy waiting to use the laser anyway), so unfortunately I had to finish the cut on the bandsaw. It turned out very rough but I was more worried about seeing it prototyped than seeing it neat.

Here’s the Illustrator file of the layers:

Screen Shot 2016 04 25 at 9 23 54 PM

With the layers (badly) cut, I quickly glued them together, trying my best to keep the layers aligned. For the aluminum version I might cut a couple of alignment holes and then tap threads so that I can run some permanent alignment screws. That way they’ll be nice and tight and aligned before welding.

Once the stack dried I took them into the wood shop and hit them with the big stationary belt sander to clean up the edges and sides.

So if you’re keeping track, I had a brainstorm and was able to use the following process to go from idea to physical prototype:

Fusion360 CAD software
Trotec Laser Cutter
Band Saw
Belt Sander

All in the course of about two hours (a little more if you count drying time). The end result?

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You can see the inside lip that the corresponding mounting block will rest against. This means that the weight isn’t being borne by the screws (as in the blueprints), but by the structure itself. That was my little idea. Yay me.
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And here it is on the upside-down frame. It works! It works GREAT! I’ll double check the measurements tomorrow but it looks great! I’ll just have to make sure that the layers are perfectly aligned before I weld them together since there is literally maybe .001 of slop in that inside joint. If I mess up the alignment it’ll be a whole lot of filing to get it to fit together. Lining up the screw holes isn’t going to be fun either. But hey, if there’s one thing I can do, it’s the slow and steady thing. I might not be the most talented guy around, but I’m stubborner and mule-headeder than anybody.

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My prototype isn’t pretty, but it does the job and I think it’s exactly the right way to go about this. I’ll make the curved outer part out of 16ga (.063″) 5052 and bend it on the slip roller, then cut and weld the curved part with the slot in it last (and probably file and sand for hours).

I’ll still have to TIG weld the edges of the aluminum once they’re cut on the Water Jet and ground down to make the little “V” shaped edges. But since I’m working in consistent 1/4″ layers, uneven heat build up shouldn’t be a problem. That’s the beauty of this design and I’m actually rather proud of my solution. I’m fairly certain that I’ll be able to use the same procedure to make the outer feet with just a few alterations for a slightly different geometry. The best news? If I bought these feet online from a builder they’d run around $900 (!!!!).

Doing them this way will be about a quarter of that.

Take that!

I feel really good about my progress lately. I had been feeling stuck lately what with the horseshoes. But all the thinking and staring off into space finally got things unjammed. I feel like I have some momentum now.

After the ankles will come the feet (a huge multi-month job) and then the motor mounts but those are both on the far side of 40 hours of TIG welding practice. But that’s basically Year 2: Legs in a nutshell. I can’t see the end of this particular tunnel but I feel like I finally have a map that makes sense.

This morning (really early… insomnia) I also bought some aluminum prep cleaner (called, naturally enough, “Alumiprep 33”) that should make the TIG learning a lot less painful. Dirty aluminum is a pain to weld and this stuff cleans it right up. Wasn’t too expensive either.

So yeah…. Center ankle!

April 23, 2016

More R2

Filed under: The R2 Project — jasony @ 9:38 pm

It’s been a busy R2 week! Feels good to get some serious time in on the build. Tonight, after spending 8 hours at Techshop (four of which were teaching a water jet class), Erin and I went out to dinner. While leaving dinner I said “I kinda feel like going to Techshop”. It’s nice that the place has such a good hold on me and I don’t get tired of it.

Now that it looks like I have a handle on the horseshoe I went ahead and cut the rest of the layers (six of them) for the other side. Then I filed off the tabs and ground down the v-grooves on the edges of each. So now I have a second stack of horseshoes all ready to weld! I might hit up Keith again to walk me through it, but this time maybe he’ll let me weld while he advises from the sidelines. I’m about ready to get started TIG welding parts.

Side story: tonight my water jet class had two people in it. Normally it has four. I really like two person classes since I can help the students more and I don’t feel as rushed. One of the men in the class was about 70 years old with a great sense of humor. Funny stories (he was a pilot as well so we could talk endlessly about planes and flying), great sense of humor, and — unusual for someone of that generation — was heavily involved in programming and microcontroller technology. We hit if off immediately and I had a great time teaching him. The only issue was that it was sometimes rather difficult to understand him on account of the fact that half of his face was missing. And one whole eye.

You see, this funny, lighthearted, intelligent septuagenarian is fighting a long battle with cancer. 8 years ago he had a tooth that wouldn’t heal and here, eight years later, he’s had one eye removed, he’s missing the teeth on one side of his head, the entire left side of his face is nearly gone from the cancer, he’s wearing two hearing aids, jokes about his lack of depth perception, and says the hardest part of his life comes every four months when he goes in for his MRI to see if the cancer has returned yet again (it keeps coming back). The hardest wait is between the MRI and waiting to see the doorknob turn and see if his doctor’s face is smiling or ashen. He calls it “getting his ticket punched for another four months”.

And now this guy chooses to spend four hours of his remaining time in my classroom learning how to use the water jet because he wants to be a Techshop member and he wants to use the tools to build cool stuff. He’s not sure if he’ll be here next year, or even six months from now. But with the time he has left he’s going to make stuff, and try to make it well. And I can’t tell you how much I enjoyed getting to know him.

R2 Horseshoe Weld Success!

Filed under: The R2 Project — jasony @ 9:20 am

Some good success today. I coated the horseshoes in JB Weld and LabMetal to fill in the little V-grooves that I ground in each side layer. It was ugly once it dried:


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Next I clamped the part in the vice with some wooden shims:

IMG 2062

Then I ground the welds and filler down with an aluminum grinding disk that Keith gave me the other night (thanks, Keith!) They looked really good after I was done. Nice and smooth and flush with the surface. Since I was using a disk and not a belt, though, it was easy to make little divots and gouges in the soft aluminum. There’s a bit of waviness on the edge of the part in this photo:

IMG 2066

So I’m ordering some Rage Gold body filler from Amazon (the same stuff I used to make the Tri Delt clamshell prop about five years ago). I’ll do a few layers of filler on the outside so I can cover up the metal edges. But before that I still need to drill out that broken screw (you can see it in that top photo). 

So in spite of the expected (and unexpected) little snags it appears that I have a clear way forward on the shoes! Really happy with the way it’s turning out.

I spent about 3 hours at TechShop this afternoon and in addition to the grinding I also did some thinking about the center leg ankle. The finished part should look like this:


with this inside (I’ve already made the rectangular part):


 I had what I thought was a shoe-in idea for this and spent some time at TechShop designing a file in Fusion 360 (what a great program), but now that I look at it in the first picture above I’m not so sure it’ll work. More thought needed.

A lot of this thinking is due to the fact that I can’t TIG weld (yet). I really should get off my butt and just do it. I’ll probably ask some advice and start that process next week. So much would be easier about this project if I could just TIG. Even badly. Grinding down that aluminum results in an amazingly clean joint (see the post-ground horseshoe pics above). But the process kind of scares me.


April 20, 2016

Horseshoe Update

Filed under: The R2 Project — jasony @ 10:11 pm

In the great-news, slightly annoying news department, I went to Techshop today and bumped into the welding instructor (a super guy named Keith Wojcik who is one of the best welders in Austin). Great guy, great teacher, great welder.

IMG 2055

I showed him the part and asked him if it was even possible to weld it and he said “come here” and wandered back to the welding room. Back there he set up the TIG welder, described what needed to happen, and then just welded it for me right there. I couldn’t believe it. The aluminum was pretty dirty so the welds ended up a little messy (absolutely not Keith’s fault), but at the end all seven layers were securely welded together. Success (so far).

IMG 2056

It’s a tack weld job and will be ground down and cleaned up, but the layers are connected. I’ll also put a coating of Lab Metal between the welds to cover the layers and then grind/sand it down until it’s smooth.

Unfortunately (you knew this was coming), I think the screws were overheated when the aluminum got hot — and it got stupendously hot. It took more than 45 minutes for the aluminum to even be movable, and even then I had to wear leather gloves. Anyway, the screws got bound in the holes. I also think that the act of clamping the parts together compressed the threads in the holes and made the screws bind even tighter.

Sooooo… when I went to take the screws out they were extremely difficult to turn. Two of them came out with a little bit of effort. But that third one? The screw head just snapped right off. Nooooo!!!! Luckily there was still a little bit of thread showing so I got some Vice Grips after the little threaded leftover…… and promptly snapped that off as well, completely flush with the surface.

Well poop.

So I have to figure out how to remove that bloody screw. That stinking #$@#@^ screw. It’s so completely stuck in there that a normal screw remover probably won’t do the trick (though I have nothing to lose by trying). What I think I’ll end up having to do is slowly destroy the screw by drilling it out with progressively larger bits. I might have to enlarge the hole and put a #10 screw in there instead of the #8 that’s stuck, but that means enlarging the mating keyhole, which introduces alignment issues (which I’ll have to figure out a solution for). There’s also the risk of breaking the welds when I clamp it on the mill to remove the screw. UGH

But hey! One of the horseshoes is welded. Better yet, Keith told me that he’d weld whatever I need. He’s also going to teach me TIG. I took his MIG class again tonight and had fun. TIG is a whole different story. I get to learn from the master.

When I left the shop tonight one of the Techshop employees said “that’s why they call it a Herculean effort”. Every step has something go wrong.

Every. Single. Step.

R2 Update

Filed under: The R2 Project — jasony @ 8:38 am

It’s been a while since an R2 update. I probably need to write a lot more but I don’t have time right now (I’m actually building instead of writing about it).

About two weeks ago I decided to mill up the little leg “cups” that hold the leg hubs. It’s an easy part to overlook. Fortunately, I was able to find some aluminum tubing with an inside diameter (I.D.) that was close. I got a 12″ piece, chopped off a 5″ piece, and proceeded to very slowly mill out the I.D. on the lathe.

IMG 2003

IMG 2004

That wall is less than .125″ thick. It’s really delicate and I was worried about milling through it so this cut took me about 2 hours. I’m slow on the lathe but the tool scares me so I play it as safely as I can.

Once I got the I.D. correct I just cut off a piece that was the right length (two, actually). The part separated early before the cutting tool had cut completely through, which I was initially upset about (oh no! sanding a delicate part!)

IMG 2005

but it turns out that the little edge you can see on the left was pushed in a few thousandths of an inch and so it fits perfectly inside the mating hole and acts as a guide! I’ll have to chamfer off a tiny amount on the inside of the hub when the time comes so the hub will clear it, but since it’s inside the leg you’ll never see it. And besides, the little guide ring makes alignment and gluing MUCH easier. So an unintended mistake turns into a win! Happy accident.

In the past week I’ve worked about 20 hours at Techshop on the Horseshoe parts. Well, one horseshoe. I water jet cut out the 8 layers (out of .125″ aluminum 6061) and test fit them together.

Here’s a pic of the sheet of 6061 before and after water jetting

IMG 2007

IMG 2014

And here are the layers stacked up on the leg (which is itself just stacked precariously and not welded yet):

IMG 2015

Great fit. I had to file the tab from the water jet off of each layer (2 tabs actually)

IMG 2053

IMG 2052

I bought a set of files from Lowes since so many of the TechShop files are corrupted with steel or not in good shape. Add it to the budget.

IMG 2054

Once I’d filed away the tabs I sandblasted each part to give each layer a bit of “bite”. My idea here was to lay down a coating of aluminum epoxy to bond the layers together. However, once I got the epoxy and did a test run on some scrap, the scrap debonded (it broke) with very little pressure. So instead I VERY carefully aligned the eight layers and clamped them together, then spent the next three hours in the machine shop drilling and tapping some holes so the layers could be held together with screws. Somewhere during this process (power washing after the sandblasting, I think) some of the layers got very slightly bent. So now my perfectly flat horseshoe ends are flayed out. Ugh. I’m going to TechShop tonight to talk to a professional welder to see if it’s possible to clamp the layers together and tack weld them. In preparation for that I spent a few hours grinding a bevel on each layer so that when they’re stacked up there’s a little “V” shaped groove on the edges between layers. Hopefully if the layers can be welded this will give the aluminum rod enough “bite” to hold the layers together after grinding off the excess material.

Keep in mind that I’ve worked about 40 hours on just this one horseshoe. I haven’t even cut the parts for the second one yet. I’ll give the welding thing a try and if it works I’ll go ahead and commit to the second one. If, however, the welding is a total bomb then I’ll step back and rethink how I’m doing the horseshoes. I really really want aluminum shoes but if it’ll delay me too much I’ll do MDF now so that I can move on. Those parts are easy to replace in the future if/when I choose to revisit them. It’s been so long since I’ve seen forward momentum that it’s easy to get discouraged. So I’m considering making some temp parts and replacing them in the future if I get stuck at a certain point. Droid building is the Everest of Nerddom, as I’ve said. So there will be some parts of the journey that feel like you’re stuck. But I don’t want to get so mired up in one part that I get discouraged and wash out.

I’m frankly terrified to weld these things. I’ve spent a lot of time (and not inconsiderable money) getting the horseshoes to this point and if they warp under the heat (something I’ve been warned about) then it’s back to square one. But if I’m so nervous about messing them up that I don’t move forward then I’ll be stuck here forever. So I guess I have to do something. Hope I don’t screw it up. I might hire a pro to do these particular parts, or at least to just tack them in five or six places so that I can come back and Lab Metal them and sand them down.

Looking forward, there are so many aluminum parts that need to be welded that I’m almost certain I’ll have to learn to TIG weld. This project is about learning new skills but TIG is extremely difficult to master and represents a major detour while I develop the skill. Probably about 40-60 hours running a mile of bead to get good. In the meantime nothing will get planned, designed, or built. But there are so many parts to weld that hiring someone to do it doesn’t make much sense. My Techshop friend Bill May gave me a pep talk the other night that helped a lot. I was getting a bit discouraged thinking about the ridiculous challenge this project represents. Bill had some really kind and encouraging words for me and encouraged me to learn to TIG and keep moving forward. Frankly, I kind of needed it and appreciated it more than I think he realized.

It seems like at every single point in this project, from major design decisions down to where to clamp a part on the mill, there is some sort of little issue that crops up. For example, while tapping the holes in the horseshoe stack I discovered that my tap was about 1/16th too short. But since the stack was already clamped and the hole drilled I had to solve the problem right then. No coming back to it later since I couldn’t take it off the mill until the holes were drilled and tapped. I managed to figure out a solution but it took a lot of seat-of-the-pants thinking. The entire project is like that: nothing easy, everything fights you. So Bill’s words were really helpful. Keep pushing ahead. Eat the elephant one bite at a time. Don’t look at the summit– just look at the next step to be taken. This will take another three or four years (if I’m lucky!) and if I think of the whole project at once I’ll just get discouraged.

Okay, onward.

April 12, 2016

Class I – Loose Fit Tolerance Chart for Holes and Bolts – Engineers Edge

Filed under: The R2 Project — jasony @ 4:07 pm

I was referring to the following chart for R2D2 aluminum fit tolerances. I was just looking at one of the engineering drawings that I have to reproduce in a year or so and inadvertently started giggling like a crazy person. What am I doing? I’m insane. I’m insane. Not until one of the other members at Techshop looked at me funny did I realize that I had just said everything out loud at full voice.

Oh, R2. You’re going to be the end of me.

Class I – Loose Fit Tolerance Chart for Holes and Bolts – Engineers Edge: “”

December 21, 2015

R2 Update

Filed under: The R2 Project — jasony @ 7:57 pm

More work on the R2 front. A lot more since my last update. The frame is pretty much finished except for the laser etching (which I’m still contemplating and, actually, reconsidering). So I’ve moved on to R2’s leg assemblies I have put a total of 43.5 hours of work into them so far (not counting stare-at-the-wall-and-think time).

Here’s what I’m trying to make this year.


and is comprised of these sub-assemblies (including the feet and battery boxes as well as some other details). I’ll need to make two of these and a shorter center leg.


The entire leg assembly has 30+ individual parts. I have to make a left leg and a mirrored right leg (as well as a less complex center leg). The part I’m working on right now is the “inside” main frame assembly of the leg that supports everything else. It’s made up of a top plate, bottom plate, four side “walls”, a curved top piece, and couple of bottom pockets that hold the side details (which I also have to make). Here is the basic structure


I designed the files in Fusion 360 and exported them as .ord files to set up on the water jet.


I took one of the two plates of 1/4″ aluminum I got for free from the anodizers (yes, they gave me about $150 in aluminum after I paid them the extremely low rate of $70 to anodize the frame (should have been $500 but they were jazzed about it being R2) and carefully positioned it on the water jet. I had to be really careful since all of the holes in the plate made it difficult to work around. In the end it took me almost an hour to get things lined up correctly.

Then I discovered that the water jet is misaligned. Whoops.

It’s actually a pretty big discovery at the shop and solves several mysteries around there. Turns out the underwater bed of the machine is off in the Y axis about 1/2″ over the 6′ front-to-back span. Seeing how the water jet has to be focussed about 1/8″ above the bed with a tolerance of around 1/16″, this was obviously not going to work. So I tore down my assembly and rotated everything 90 degrees, thus minimizing the error. I also had to regenerate a brand new water jet file. All told, I took about 2.5 hours on what should have been a 30 minute setup.


After doing a dry run to make absolutely sure everything worked, I held my breath, started up the machine, and hit “execute”.

Here are a few videos of the machine in operation. It may be a costly beast, but what it can do in a very short period of time is just amazing. I really couldn’t do this without spending weeks in the machine shop, and even then I might get it wrong with my level of skill. The water jet is truly amazing.

23 minutes later I had one of the legs! Success!

Here’s a shot of the final plate with the legs cut out (after I washed it off with some water):


Or… so I thought at the time.

Since everything was already set up and looked correct I went ahead and plopped the other plate down on the machine, calibrated and clamped it down, and cut a second set of leg plates. The pump mysteriously shut down halfway through (we think that the switch has a short in it) but a quick restart and I was back in business. Total cut time was just over 47 minutes. *whew*!

Unfortunately, upon my test assembly I realized that I had used the *wrong file* and my ‘side-wall’ rectangular pieces were cut .25″ too wide! This was a much better mistake than cutting them too short however, since I needed to mill off the taper that is introduced by the water jet anyway. Well, I thought it wasn’t going to be too big of a deal. I went back into Techshop early this morning and ended up spending about 8 hours in the shop slowly milling off that extra .25″ of width. So yeah…. lots of labor to correct a silly mistake, but ultimately I got some good manual mill practice as well as some really nicely made parts. I’m very happy with the way things are shaping up.

The next step is to decide how I’m going to make the top curved piece of the legs. I’m probably going to water jet that as well (to a man that has only a hammer, every problem….). I’ll have to come up with a 1.25″ thick piece of aluminum that’s big enough for the 6″ wide piece. It’ll be a chunk of change but I might be able to find it in the drop bin at the metal place (sold by the pound). Cutting something that will be a beast, too, but it’s the only way I can figure now.

Speaking of which, I spoke to the machining instructor, Jack Withers, at Techshop about the leg “horseshoes”:

Shoulder Horseshoe-1.jpg

I’ve been through three or four ideas about how to make these but the best idea I’ve come up with is to make the 1/8″ slices on the water jet (yeah, yeah) due to the fact that the inside of the hub has those offset gear pieces. My concern is that the outside of the horseshoe will show those “bread slices” through the paint. But I think that if I lay down a coat of lab metal and then wet sand (and sand, and sand) then I should be able to cover up the slices.

Of course, doing it this way means that I have to drill and tap holes so that I can screw the slices together from the backside. But…. of course… the vice in the machine shop is 1/8″ too narrow for the horseshoes. So. I’ll have to disassemble the vice and figure out some way to make it slightly bigger in order to accommodate the wider stock. Always an adventure.

But that’s for later. Now I need to spend several weeks thinking about the leg assembly. There’s an interesting inside piece that you can just barely see that looks like this:


How in the world am I going to make this? No idea yet…

November 19, 2015

Anodizing Successful!

Filed under: The R2 Project — jasony @ 10:26 am

The company said 10 days for the anodizing but the employees were so excited about having an R2 frame to work on that they put me at the front of the line. The big boss at the shop told me that they all took special care walking the parts through the 20 (!) tanks required for the whole anodizing process.

So today, after less than 48 hours in the shop, they called and told me that R2 was done! I was thrilled to go pick it up (and took them some pizza as a lunchtime thank you as well). Then I spent some time doing a tolerance check (that is: I assembled it!). The glossy finish I gave the parts was totally worth all the work. It looks amazing.
Here are some pics of the frame with all of my current pieces in place. I still have to design and laser etch the circuitry patterns but I’m thrilled that this part is done. Also, much relieved.

I had to get the dome out of its box and do a test fit, of course. It drew all kinds of attention at Techshop. People love R2.

Long, long way to go but this was a major milestone. Great to see it coming together.




Proud R2 papa

IMG_3985 copy.jpg

November 16, 2015

Polishing Pics

Filed under: The R2 Project — jasony @ 2:06 pm

So I just realized that I haven’t posted any pics of the polishing process (say that five times fast). I’ll update you a bit.

Since finishing the frame a few months ago I got online and researched sanding and polishing aluminum. There’s a TON to learn when you prep for anodizing. I opted to go the cheap and easy route.

Hahahah, but seriously folks. I had you there, didn’t I?

Instead of using the TechShop buffing wheels that may have been corrupted with steel (a deadly combination when you’re anodizing aluminum), I bought several different brand new buffing wheels. I also got two different types of aluminum polish (Mother’s Aluminum polish and Mother’s Billet polish). But before I even got to that point I had to sand.

And sand. And sand.

Here are two pics of a part when it’s ready for sanding;



You can see the milling marks, scratches, dings, crud, and ink from the plant. The aluminum feels rough and the edges are sharp. Yes, it’s a completed part but it’s still a visual mess.

The vertical rods (3/4″ solid aluminum) are about the same:


Yuck. The aluminum gets beaten up and scratched during the milling, forming, and tapping process, and it doesn’t start in a very good condition when you buy it anyway.

So I bought a set (which ended up being two sets) of wet/dry aluminum sandpaper. I also got a cheap pneumatic sander. Using the sander I hit the aluminum with 400 grit w/d sandpaper until I removed all of the basic scratches. If I had to do it again I’d have probably started at 200 grit. 400 took forever to remove the scratches. This is metal, after all. I’d work on a little 6×6 section for probably ten minutes before the big dings had been replaced by 400 grit sanding marks.

Next, I repeated the process with 800 grit, then 1000, then 1500, then 2000, then finished off with a 3000 grit wet/dry pad. For all 38 pieces of the frame. Total time spent sanding was about 20 hours over several weeks. It was also a mess with wet dirty aluminum “sawdust” flying everywhere. Even wearing an air mask, shop apron, gloves, and goggle/faceshield, I still ended up coming home looking like a coal miner.

2015-09-26 15.57.27.jpg

For the aluminum rods I had to first use a hard wheel to remove the worst of the scratches:

(Thanks to Sean for filming)

Once I had the parts sanded up to 3000 grit I installed a Sisal buffing wheel onto the new grinder/polisher/sander at TS. It’s a great tool! Big enough to do a project like this.

I’m simulating this pic with a non-spinning wheel:

I then put white polish on the sisal wheel and made a pass over each part to start to bring out the shine. Once all 38 parts were done I installed a soft cotton polishing wheel, put red jeweler’s rouge on it (the kind that you use on fine silver and gold), then started over and polished each piece until they sparkled. But I wasn’t done yet!

I then put the pieces into my storage box that I’d made at TechShop on the laser cutter (the box is in the “Because-I-Can” category). Then, one by one, I took each piece out and put a coating of Mother’s aluminum polish on them, followed by a final coat of Mother’s Billet Polish. These last two use a chemical reaction to get any surface oxidation off and give it a final, final polish.



If you’re keeping track, all of the above means that each coat gets ten different passes of progressively higher grits. The first grit, 400, is usually my final grit when I’m woodworking. For R2, that was the starting grit. By the end of the process I’ve polished the 6061 aircraft aluminum up to a chrome-like shine.

After a total of over 600 hours of work, here is the final result. Aluminum ain’t supposed to look like this, folks:



Finally, I brought the parts home and wiped them down with a soft rag to get any little bit of polish remaining off of them before I took them to the anodizers.

The anodizing company is doing the job for an extremely inexpensive rate. When the plant manager saw that it was an R2 frame he was really excited about it. The normal charge from another company is $500 but he’s doing it for $70 (basically cost, I think). I told him that all of his employees would get their names etched into the frame as thanks. Might even buy them pizza when I pick it up. It’s a really screamingly great price for a job like this. They even agreed to mask and plug any questionable holes that might interfere with the process. They’re going above and beyond since it’s a nice change from the generic metal unidentifiable parts that they usually do.

Why go to all that work to polish up to such a ridiculous shine if the parts are only going to be anodized black, you ask? Well, the final color will be black, but the final finish takes on the finish of whatever the unanodized surface looks like. If it’s bead-blasted then the finish is matte. A brushed aluminum finish will give you a brushed anodized look. And a stupidly-polished aluminum will look something like this:


So thats where the project stands right now! I have to admit that I’m a little nervous knowing that the box of parts is sitting in the anodizing warehouse. I’ll be glad when I get it back.

Frame Away!

Filed under: The R2 Project — jasony @ 1:00 pm

Just dropped it off at Brooks industrial coatings here in North Austin. The plant manager could see how nervous I was at turning it over. When I showed him a picture of the whole frame assembled he gestured me over to where his four employees were racking parts.

“Okay, guys, group meeting. We got a fun one here. This is Jason. Jason, take it away.”

So I took three minutes to tell the guys about the 600 hours of work, learning to machine, 20+ hours of wet sanding and polishing, etc. When I said “I’m building an aluminum R2D2 their eyes lit up and they all went “coooool”. Then Bob (the manager) said, “alright guys, treat this one like a fine lady”. So I still feel nervous but pretty good. He told me to call in a few days to see if he has any questions. Otherwise it should be ready in about 10 days.

Off to the Anodizers

Filed under: The R2 Project — jasony @ 11:31 am

I’m taking my box of R2 frame parts to be anodized today. Fingers crossed hard. I just want to make sure nothing happens that could ruin almost 600 hours and over a year of work. I’ll know in a week or so.

November 15, 2015

Circuit Patterns

Filed under: The R2 Project — jasony @ 11:19 pm

Erin wants to stage an intervention.

I’m going to take R2’s frame to the anodizer this week (I need to write up a whole post on that with pics, actually). After it’s anodized I wanted to laser etch a cool circuitry pattern into the black anodization layer. After some extensive checking around online for cool scalable vector circuit patterns, the best I could come up with was this:


Unfortunately, when you blow it up to the 18×18″ diameter of R2’s main rings you get this:

Screen shot 2015-11-15 at 11.15.09 PM.jpg

Way too fuzzy and indistinct for a good quality etch, especially considering the amount of time and work I’m putting into the frame.

So I’ve decided that I need to zoom way into that top picture in Illustrator and recreate it by hand on a separate layer. Only then can I get a really great scalable jpg. Erin couldn’t believe that I was going to do it (hence the intervention comment). Fortunately, though, it’s not all that bad. the pattern above is a 9×9 tiled image. So if I isolate the center 1/9th section and recreate it I can easily tile it. It should only take a week or so working about 30 minutes per day. No problem.

October 15, 2015

End of Sanding

Filed under: The R2 Project — jasony @ 7:55 pm

Finally finished sanding the frame pieces! I took the four curved front pieces and sanded them up to 3000 grit (wet-sanded). It took almost three hours. Ugh. I’m so glad to be done with that.

I still have about six to ten hours of polishing with the industrial buffer (and four more grits of rouge followed by aluminum polish and then billet polish) but the really nasty job is done. When I finished I took off my N95 mask and it was covered in powdered aluminum. So glad I wore that thing.

Anodizing is getting closer. I’ll hopefully be able to take it to the anodizer in a few weeks.

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